Air conditioning apparatus



June 116 1936.

M. F. MAY 2,044,538

AIR CONDITIONING APPARATUS 2 Sheets-Sheet 1 Filed April 4, 1935 7? 7?axzae m,

June 16, 1936. M. F. MAY 2,044,538

AIR CONDITIONING APPARATUS Filed April 4, 1955 2 SheetsSheet 2 lily. 6?,

Patented June 16, 1936 UNITED STATES PATENT OFFICE AIR CONDITIONINGAPPARATUS Maxwell F. May, Palos Park, 111.

Application April 4, 1935, Serial No. 14,725

15 Claims.

This invention relates to air conditioning apparatus, and moreparticularly to such apparatus wherein at least two speeds of aircirculation are provided.

One feature of this invention is that it provides a gentle current oftempered air; another feature of this invention is that it provides,when required, a stronger current of heated air; still another featureof this invention is that it either cools or heats the air, as theoutside temperature requires; yet another feature of this invention isthat it is completely automatic in operation; other features andadvantages of this invention will become apparent from the followingspecification and the drawings, in which- Figure l is a side elevation,partly in section, of an installation embodying my invention; and Fig. 2is a schematic diagram of the electrical control circuit.

Conventional air conditioning systems are so constructed as to provide agiven volume of air at a given temperature to the room which it isdesired to heat or cool and control of the temperature level in the roomis achieved through starting and stopping this flow of air. This is trueboth of hot air systems used for heating and air conditioning systemsused for cooling. This method is open to several objections. One objection is that in the period during which the system is inoperative theair in the room tends to stratify. When the air current again starts toflow, moreover, there is a distinct and unpleasant sense of immediatetemperature change, resulting from the entrance of a strong current ofair at a considerable temperature gradient with respect to the room airinto the stratified and quiet air of the room.

This invention obviates these objections by providing, when the outdoortemperature requires it, a gentle current of tempered air continuouslyflowing into the room. At outdoor temperatures below 55, for example, agentle current of air having a small temperature gradient with respectto the air in the room, for example 20 or 25 higher, would flowcontinuously. This current of tempered air would avoid Stratification ofthe air in the room and would provide a certain amount of heat, at suchlow air speed and low temperature gradient as to be entirelyunnoticeable to any occupants of the room. When the temperature in theroom, however, finally drops below the desired setting, the system isstepped up to furnish a much larger volume of heated air, as for exampleair at 145 or 150. While this stronger current is noticeable, there isno unpleasant feeling of sudden temperature change. since there has beena continuous gentle current of slightly warmed air coming into the room.

In the particular embodiment of this invention illustrated herewith, abuilding I is shown hav- 5 ing outer walls II and I2, rooms l3 and I4,and a basement 15. The wall or partition I6 between the rooms I3'and I4is shown provided with an air duct ll, which ductopens into the rooms,as at l8 and I9. Suitable air return means are provid- 10 ed, as forexample the conduits 20 and 2|. The duct ll is-considerably enlarged inthe basement, and contains therein heat transfer means or coils, as thecoils A, B and C. A blower or fan 22 is provided to force air throughthe duct, which fan is driven by an electric motor D, here shown as a2-speed motor. The duct ll would in a commercial installation, beprovided with humidifying and dehumidifying devices to regulate themoisture content of the air being supplied to the rooms. Such devicesare not illustrated here, however, since they form no part of thepresent invention. A boiler 23 furnishes hot water and steam to thecoils, and is provided with automatic firing means, here shown as thestoker 25 24 driven by the motor 25. The boiler is provided with anaquastat 26, normally set to keep the boiler water temperature atapproximately 170, and with a steam pressure switch 21.

When the system is set for heating, valves 29 30 and 30 are manuallyclosed, valve 3| is opened wide, and throttle valve 32 is partly opened.A gravity circulation is thus provided for the hot water in the boilerout through the tempering coil C, down through the valve 3| and back 35through the return pipe 33 to the boiler. The amount or rate of waterflow through this gravity system may be regulated by adjustment of thethrottle valve 32. This gravity system is also provided with anautomatically operated valve, here shown as a solenoid operated valve34, which valve is normally closed, but is opened wide upon an urgentdemand for heat by the room thermostat 35 located for example in thetemperature responsive means or thermostat box 35. The valves 32 and 34are actually at the same vertical level, but are here shown inperspective. A steam pipe 3'! serves to energize the heating coil A,that is, to furnish it with steam when steam pressure is up in theboiler, a return line being provided by the steam pipe 38 and the returnpipe 33.

In the summer, when the system will be used only for cooling, valvesv39, 29 and 30 are opened, and valves 3|, 32 and 34 are closed. Coldwater, or other cooling medium, is forced through the the boiler.

pipe 40, the coils B and C, and out the pipe 4|. The pipe 40 is providedwith an automatically operated valve 42. This valve, in combination withone of the cooling thermostats 43, serves to regulate the flow ofcooling medium through the coils B and C, in accordance with thetemperature conditions of the room. It will be noted that even when thesystem is thus set for cooling a sudden drop in outdoor temperaturewould cause the thermostat 28 to shift the electrical control systemover to heating and the air being forced through the duct would beheated by the steam coil A as soon as steam pressure was raised in Thusthe system is able to automatically react to unexpected changes inoutdoor temperature, even though it would not provide the desirablegentle current of tempered air when the various manually operated valvesare set in the positions last described.

Referring more particularly to Fig. 2, it will be noted that the outdoorthermostat 28 controls a 2-pole 2-throw relay 44. The poles'of thisrelay are supplied with current to energize the control system, as bycommercial 110-volt AC lines 45 and 45. In the construction illustratedhere, the thermostat. is arranged so as to remain open while thetemperature is below 75,

and to close when the outdoortemperature is above that point.

When the thermostat 28 is open the relay makes connections between lines45 and 4B and the lines 41 and 48, which lines supply the heatingcontrol system with energy. When the outdoor temperature rises above thepredetermined value of 75, the thermostat 2B closes, thus closing therelay 44, and causing the lines 45 and 45 to energize the lines 49 and50, which lines supply current to the cooling system.

Assuming the outdoor temperature to be such that the heating system isenergized, the room thermostats 35 and 5| will be energized throughtheir respective transformers. These thermostats are preferably setabout 1 apart, for example, thermostat 35 being set at 71 and thermostat5| at 72. Whenever the room temperature is below 72 the temperatureresponsive device or room thermostat 5| will close, thus energizing the2-pole single throw relay 52, which closes the circuit to the fan motorsupply lines 53 and 54. This circuit is completed through either of twoswitches in parallel, which switches are here shown as an aquastat 55located in the coil C, or in the pipe leading thereto, and the limitswitch 56, which switch is located in the air duct. Should both the airin the duct and the water in the tempering coil C be cold, the circuitwill thus remain open to the fan motor, in order to prevent cold airfrom being forced into the room. As long as there is hot water in thecoil C, however, or the air in the duct is warm, the circuit will becompleted and the fan will operate.

The fan motor D is here shown as a 2-speed motor, controlled by the2-pole 2-throw relay 57. This relay, when not energized, connects themotor feed lines 53 and 54 with the low speed connections 58 and 59. Twoswitches or controls are provided in connection with the relay 51, thesteam pressure switch 21 and the thermostat 60. The steam pressureswitch 21 is located in the boiler and closes whenever the steampressure, as a result of firing of the boiler, is high enough toenergize the heating coil A. The thermostat 60 is located outside thebuilding, preferably adjacent the thermostat 28, and serves to energizethe relay at outdoor temperatures above approximately It may thus beseen that when the heating control system is operative the fan motor isstepped up to high speed by the closing of the switch 21 as soon asthere is suflicient steam in the coils A to heat the coils to thedesired tem- 5 perature. When the system is set for cooling, on theother hand, outdoor temperatures above 90 cause the fan to operate athigh speed, thus adjusting the capacity of the cooling system to theoutdoor temperature. 10

The stoker motor 25 is supplied with current either through the lines 6|and 62, or through the lines 53 and 64. Current through the lines 6| and62 is controlled by the aquastat 26, and is dependent upon boiler watertemperature. As 15 normally set, the aquastat serves to keep the waterin the boiler always above 170. The lines 63 and 64 have their circuitcompleted to the main supply lines 45 and 46 through the doublepolesingle-throw relay 65. This relay is con- 20 trolled by the roomthermostat 35. The relay 65 also has in combination therewith asingle-pole double-throw switch which serves to energize theelectrically operated valve 34 in the supply line to the tempering coilC. When the relay 55 25 is energized, upon a more urgent demand for heatby the room thermostat 35, the circuit to the stoker motor 25 iscompleted and the valve 34 is electrically opened wide. This valve maybe solenoid operated, as is valve 42 in the cooling 30 line. Energy tooperate both of these automatic valves, 42 and '34, is supplied by lines65 and 61 from the secondary of a step down transformer 68. Current tooperate each of the various relays illustrated is, in the usualcommercial form, 35 supplied by a separate transformer built integrallywith the relay.

Assuming the outdoor temperature to be about 60, the thermostat 28 wouldbe open and the control system for heating would be energized 40 throughthe lower contacts of the relay 44. Whenever the room temperature dropsbelow 72, the closing of the thermostat 5| energizes the low speedconnections to the fan motor. A gentle current of air is thus drivenupwards through the 5 duct, passing through or over the tempering coilC. The manual throttle .valve 32 is preferably permanently adiustedat apoint which will permit just sufficient gravity flow of hotwater throughthe coil C to raise the temperature of the 50 air to the duct, at lowfan speed, to about This gentle current of air warms the room untilthetemperature has risen above 72, whereupon the thermostat 5| opens andthe system ceases to operate. Should the outdoor temperature be muchlower, however, as for example 30, the heat losses from the buildingwould be slightly greater than the heat that could be supplied by thesystem operating with the fan at low speed and the tempering coil only.There will thus 60 be, a constant current of temperate air flowing intothe room, since it will never be able to raise the temperature above,72.Whenever the room temperature drops below 71, however, the thermostat 35will close, thus energizing the o5 stoker motor-and opening theautomatic valve 34 wide. There will thus be a greater flow of hot waterthrough the coil C, and a consequent slight rise in temperature of theair being supplied to the room. As soon as the steam pressure 7 in theboiler has risen to a point sufficient to properly energize the heatingcoil A, the steam pressure switch 21 closes, thus energizing the relay5'! and raising the fan to high speed operation. A strong current ofheated air will thus be sup- 75 aosasss a plied to the room until suchtime as the temperature at the thermostat box 36 rises above 71, atwhich timethe thermostat 35 will open, thus closing the valve 34 andrendering the stoker motor inoperative. The fan will continue to operateat high speed, however, until the steam pressure has dropped sumcientlyto allow the steam pressure switch 2'! to open, whereupon the fan willdrop to low speed and again supply the continuous current of temperedair.

When the outdoor temperature is above the point for which the thermostat28 is set it will close, energizing the relay it and switching thesystem over to cooling, assuming that the manual valves 39, 29 and 30are open. These valves are manually operable, rather than automatic,since they would only have to be set in the spring and fall. Two coolingthermostats are provided in the room, 43 and These thermostats arepreferably set about 3 apart, for example thermostat 69 may be set toclose at 76 and thermostat 33 set to close the contact 10 at 79. Thethermostat 69 controls the relay 71, which is similar to relay 65, whilethe thermostat 13 controls the automatic valve 62, opening the valveabove tem-' peratures of 79 and closing it below that temperature. Thevalve t2 controls the flow of cooling medium through the cooling coils.As long as the outdoor temperature is below 90, thus leaving thethermostat 60 open, and the room temperature is above 76, thus keepingthe thermostat 69 closed, the fan motor will operate at low speed toforce a gentle current of air through the ducts and thus give aneffective cooling action without the flow of any cooling medium throughthe coils B and C. As soon as the room temperature rises above 79,however, valve 32 will be opened by the action of thermostat (i3, andthe cooling medium will flow through the cooling coils in the duct. Thefan will continue to operate at low speed, and the cooled air will flowthrough the ducts into the room until the room temperature drops below79, whereupon the valve 32 will be closed by the thermostat 53. Outdoortemperatures above 90 close the thermostat. 60 and thus cause the fanmotor to operate at a high speed, insuring suihcient cooling capacity inthe system at high outdoor tempera tures.

It will be noted that, in the steam boiler system heretofore illustratedand described, the tempering coil C is supplied with hot water from theboiler 23 by gravity flow, although the coil A is energized by steamwhen steam is raised in the boiler. Should it be desired to have theentire system hot water operated, the heating coil A would be energizedby hot water circulated through it by a force pump. The tempering coilC, however, would still be supplied by gravity flow. The gravity flowfeed of the tempering coil is an advantage, since in cold weather thiscoil oper ates continuously. Were the tempering coil to be energized byforced feed of hot water, for example, the circulating pump would haveto operate continuously in cold weather.

While I have shown and described certain sinbodiments of my invention,it is to be understood that it is capable of many modifications.Changes, therefore, in the construction and arrangement may be madewithout departing from the spirit and scope of the invention asdisclosed inthe appended claims, in which it is my intention to claimall novelty inherent in my invention as broadly as permissible, in viewof the prior art.

rendering said fan operative at a low speed upon a demand from saiddemand means; means rendering said main heat transfer means opera tiveupon a more urgent demand from said demand means; and means renderingsaid fan erative at a high speed when said main heat transfer means isoperative.

2. Apparatus of the character described, in eluding: an air duct adaptedto supply air to a room; means in said duct for heating. said air; meansin said duct for continuously tempering said air; temperature responsivedemand means in said room; means for forcing a gentle current of airthrough said duct upon a demand from said temperature responsive means;and means -for rendering said heating means operative and for forcing astrong current of air through said duct upon a more urgent demand fromsaid temperature responsive means.

3. Apparatus of the character described, ineluding: an air ductadaptedto supply air to a room; a steam coil for heating said air; a hot watercoil for tempering said air; temperature responsive demand means in saidroom; a fan adapted to force said air through said duct, said fan havingat least two speeds; means rendering said fan operative at a low speedupon a demand from said temperature responsive means, whereby a gentlecurrent of tempered air is forced through said duct to said room; meansfor energizing said steam coii upon a more ingent demand from saidtemperature responsive means; and means for rendering said fan operativeat a high speed when said steam coil is energized.

l. Apparatus of the character described, th eluding: an air duct adaptedto supply air to a room; a steam coil for heating said air; hot watercoil for tempering said air; "temperature responsive demand means insaid room; a second temperature responsive demand means in said room; afan adapted to force said air through said duct, said fan having atleast two speeds; a boiler continuously supplying said hot water coilwith water; means for rendering said fan operative at a low speed upon ademand from said first mentioned temperature responsive means, whereby agentle current of tempered air is forced. through said duct to saidroom; means for generating steam to energize said steam coil upon ademand from said second mentioned tempera ture responsive means; andmeans for rendering said fan operative at a high speed when said steamcoil is energized.

5. Apparatus of the character claimed in claim 4., wherein said secondmentioned temperature responsive means is responsive to a temperatureabout 1 lower than that for which said first mentioned temperatureresponsive means is set.

6. Apparatus of the character described, ineluding: an air duct adaptedto supply air to a room; means in said duct for cooling said air;temperature responsive demand means in said room; means for forcing agentle current of air through said duct upon a demand from saidtemperature responsive means; and means for rendering said cooling meansoperative upon a more urgent demand from said temperature responsivemeans, whereby a current of cooled air is forced through said duct. I

7. Apparatus of the character described, including: an air duct adaptedto supply air to a room; means in said duct for cooling said air;temperature responsive means in said room; means for forcing a currentof air through said duct upon a demand from said temperature responsivemeans, said means including a fan having at least two speeds;temperature responsive demand means exposed to the outdoor temperature;and means whereby said last named temperature responsive means causessaid fan to operate at a -high speed when said outdoor temperature isabove a predetermined point.

8. Apparatus of the character claimed in claim 1, wherein the auxiliaryheat transfer means is continuously fed by a gravity flow of hot water.

9. Apparatus of the character claimed in claim 2, wherein the temperingmeans comprises a coil continuously fed by a gravity flow of hot water.

10. Apparatus of the character claimed in claim 3, wherein the hot watercoil is continuously fed by gravity flow.

11. Apparatus of the character claimed in claim 4, wherein the hot watercoil is supplied with water from said boiler by gravity flow.

12. Apparatus of the character described, including: an air duct.adapted to supply air to a room; a boiler; main heat transfer means, insaid duct, connected thereto; auxiliary heat transfer means, in saidduct, connected thereto, said means being energized by hot water fromsaid boiler; temperature responsive demand means; and means, responsiveto a demand from said temperature responsive means, forv raising steamin said boiler, whereby said main heat transfer means is energized.

13. Apparatus of the character described, including: an air duct adaptedto supply air to a room; temperature responsive demand means in saidroom; a steam coil for heating said air; a hot water coil for temperingsaid air; a boiler supplying said hot water coil continuously with hotwater; means, responsive to a demand from said temperature responsivemeans, for forcing a current of tempered air through said duct to saidroom; and means, responsive to a more urgent demand from saidtemperature responsive means, for raising steam to energize said steamcoil, whereby a current of heated air is forced through said duct.

14. Apparatus of the character claimed in claim 13, wherein said hotwater coil is supplied continuously with hot water from said boiler bygravity flow.

15. Apparatus of the character described, including: an air duct adaptedto supply air to a room; temperature responsive demand means in saidroom; main heat transfer means for heating said air; a hot water coilfor tempering said air; a boiler supplying said hot water coilcontinuously with hot water; means, responsive to a demand from saidtemperature responsive means, for forcing a current of tempered airthrough said duct to said room; and means, responsive to a more urgentdemand from said temperature responsive means, for energizing said mainheat transfer means, whereby a current of heated air is forced throughsaid duct.

wMAXWELL F. MAY.

